Solid or viscous substances which may cause obstruction
to the flow in a sewer or otherwise interfere with the operation of
the wastewater treatment facilities. Unless explicitly allowable by
a written permit, such substances include, but are not limited to,
grease, garbage with particles greater than 1/2 inch in any dimension,
animal guts or tissues, paunch manure, bones, hair, hides or fleshings,
entrails, whole blood, feathers, ashes, cinders, sand, spent lime,
stone or marble dust, metal, glass, straw, shavings, grass clippings,
rags, spent grains, spent hops, wastepaper, wood, plastics, gas, tar
asphalt residues, residues from refining or processing fuel or lubricating
oil, mud, or glass or stone grinding or polishing wastes.